This invention, an anamorphic light beam expander, relates to the field of optical beam manipulation and in particular, to an in-line anamorphic light beam expander for use in optical disk data storage systems, wherein the active optical elements comprising the active optical path are either fixed stationary components or single unit optical elements.
Anamorphic light beam expanders utilizing optical prisms are well known in prior art optical systems. In the more sophisticated optical storage devices, however, it is desirable to reduce the number of optical components to a minimum in order to meet the space constraints dictated by the equipment design, to minimize transmission losses, and to reduce the number of elements which can contribute to alignment errors. Space restrictions have increased the need for simplification of known anamorphic optical expanders which utilize prisms only.
Beam expansion by multiple prism devices accomplished in the prior art poses tedious and lengthy calculations in order to establish the precise prism locations within the device. Additionally, the task of precision assembly becomes even more tedious with a plurality of components.
Two approaches have been used in the prior art to avoid the complicitly of design and construction of multiple prism beam expanders. In the first, use of a minimum number of prism components necessary to accomplish desired beam expansion; and in the second, use of prisms which make use of special incident angles, such as Brewster's angles, thereby simplifying arduous design calculations and construction.
The present invention is an improvement in that the light beam expanding/contracting device uses the minimum number of prisms necessary to perform the expansion/contraction required, and employs additional light beam directing optic elements to maintain precise light beam direction within the assembly.